Summer officially gets underway on Monday at 6:28am and unlike last year where the first few days of the new season featured the only significant hot weather in the region for summer, I think this go around there should be at least 3 or 4 periods in the months ahead where the mercury tops the 80 degree mark and maybe even 90.  At least so far during the warm weather season we have soared above 90 in the area once or twice back in May and depending on how much wet weather ends up impacting our region, we'll have to see if 90 pops up again.  On average in a typical summer in Wausau temperatures hit 90+ about 6 times, while up in Rhinelander the average is 4 times per summer.

On to the weather pattern at hand.  Obviously the last 6-10 days (June 6th-16th)  in the Wisconsin River Valley were rather gloomy and damp.  Highs did not make it out of the 60s for 8 out of 10 days, and one of those days the high in Wausau was a cool 57 (June 8th).  Since hitting June 17th, the jet stream has shifted farther north and  brought in a more seasonable, warmer and more humid air mass.  Of course with that also comes greater odds for thunderstorms and potentially severe storms for Thursday night into Friday morning and then again Friday afternoon and evening.  Let's breakdown what could be on tap.

Update: Friday PM

Well Thursday evening and night turned out pretty much as I expected locally and for the folks back in Minnesota as well.  There were numerous tornado sightings in SE Minnesota, a couple just west of the Twin Cities, another near Breezy Point in N/C Minnesota and lastly a twister in Pine & Burnett Counties near the St. Croix River.  For more details on the results of the tornado damage survey check out the NWS Twin Cities and NWS Duluth websites.  Locally we did get some good downpours and downed trees in Adams, but the storms were a shadow of their former selves by the time they did reach our area.

As for Friday, there was a big wrench thrown into the works by a complex of morning storms that trucked across Iowa and continued eastbound through southern Wisconsin, Illinois, into Michigan and Indiana.  The cold front will still manage to across through our area Friday night, but much of the moisture and instability has been confined well to our south thanks to those storms.  So in a sense, I was right in thinking not all of our area would be impacted, although I need there to be at least one storm to make that really be true, otherwise it goes down as a bust.  Neverthless, a great weekend of weather is on tap, followed by a return of unsettled weather for Monday and Tuesday.

Previous thoughts on the weather:

On Thursday afternoon, a warm front extended from northwestern Minnesota southeast into Iowa and was the focus for the development of storms that were producing hail up to golf ball size in the early afternoon in northern Minnesota.  This was just the beginning to what likely will be a severe weather outbreak across much of Minnesota and Iowa heading into the evening with a good risk of storms that produce large hail, damaging winds, torrential downpours of rain and possibly a few tornadoes.  As these storms become more organized shifting into the evening on Thursday they will likely consolidate and head east toward North Central Wisconsin for the nighttime hours.  The risk for tornadoes should decrease, but it appears likely that damaging winds and heavy rainfall is a threat locally, with possibly still some storms that produce hail.  This will be the first round of unsettled weather to slide on through.

Round 2 is going to be associated with a cold front that is forecast to push across the area for Friday afternoon and evening.  The somewhat trickier part of figuring out the severe weather threats in this case is how quickly will the atmosphere recovers from the band of storms earlier in the day?  If the clouds break up by mid-morning and provide for a fair amount of sunshine into the early afternoon in advance of the front, then I can see  enough instability developing that storms that trigger damaging winds and hail, along with the heavy downpours.  Also in contrast to the AM version, the afternoon thunderstorms will be scattered in nature, so not everyone may be impacted.  No less, once the cold front shifts to the east by Friday evening, the weather should settle down for the weekend.  Less humid, still comfortably warm and a decent amount of sunshine.  However, peering down the road toward Monday through Wednesday, another wave of low pressure is anticipated to head toward the western Great Lakes.  This could again spell trouble for us with more storms that could be strong to possibly severe.  Pinning down several days in advance the extend that damaging storms could take place is not very clear cut, primarily due to the fluctuation in available moisture and whether all of the ingredients come together.  For now, the chance is out there for the early part of the work week while highs climb to around 80.

So that's how things are shaping up as of Thursday afternoon for the days ahead.  If severe weather does impact our area, be sure to check back in for a recap of the effects of these storms.